This article presents evidence that, in the early 1990s, the World Health Organization (WHO) had been overseeing massive vaccination campaigns in countries such as Nicaragua, Mexico and the Philippines, in which tetanus vaccines containing human chorionic gonadotrophin (hCG) had been given to large numbers of women. Although hCG is a natural hormone involved in pregnancy, when it is "introduced into the body coupled with a tetanus toxoid carrier, antibodies [are] formed not only against tetanus but also against hCG... when a woman has sufficient anti-hCG antibodies in her system, she is rendered incapable of maintaining a pregnancy." (Emphases added)

This article abstract shows that the contraceptive effects of vaccine-delivered human chorionic gonadotropin (or rather "a synthetic peptide antigen representing the aminoacid sequence 109-145 of the C-terminal region of the β subunit of human chorionic gonadotropin (hCG-β)") was known to the World Health Organisation as early as 1988. The abstract states that "potentially contraceptive levels of antibodies to hCG developed in all subjects. In the highest vaccine dose group, the results gave promise of a contraceptive effect of six months' duration." (Emphases added)